The present invention relates to an apparatus for forming a coating film (coating film formation apparatus) by coating a solution for an interlayer dielectric film on a substrate in a manufacturing process of a semiconductor device, and an apparatus for curing the coating film for the interlayer dielectric film on the substrate.
The manufacturing process for a semiconductor device includes a step of forming an interlayer dielectric film (hereinafter referred to as xe2x80x9cILDxe2x80x9d) in accordance with a Spin on Dielectric (hereinafter referred to as xe2x80x9cSODxe2x80x9d) system. The interlayer dielectric film formation methods in accordance with the SOD system include a Sol-Gel method, a SiLK method, SPEED FILM method, and a FOx method. In each of these methods, a solution for forming the interlayer dielectric film is spin-coated on a substrate. The film thus coated is cured by annealing in the SiLK method, SPEED FILM method, and FOx method except the Sol-Gel method.
In such an annealing process, a plurality of wafers having a coating film thereon are loaded into a heating furnace in lots. After heating at a high temperature for a predetermined time, the wafers are unloaded from the heating furnace in lots, transferred to a cooling unit by way of a transfer passage, and cooled to a predetermined temperature.
However, the annealing (thermosetting) is performed in a batch since the wafers of a single lot are heated in a furnace of a high temperature. Therefore, it is impossible to accurately control temperature of the wafers one by one.
In addition, although the annealing treatment is performed in an inert gas ambient, it is difficult to control the concentration of the inert gas when the semiconductor wafer is transferred to a cooling unit after the heating process. In other words, it is difficult to maintain a low oxygen concentration. As a result, the interlayer dielectric film may be oxidized. For these reasons, it has been strongly desired that the wafers are annealed one by one by a single-wafer processing method using a hot plate while preventing oxidation of the interlayer dielectric film.
However, since the interlayer dielectric film is annealed at a high temperature, a temperature sensor used in a hot plate of a conventional apparatus and an inter-lock sensor for preventing an excessive temperature increase cannot be used. Therefore, if the annealing is performed by the hot plate, it is difficult to control temperature. In addition, even if only the annealing is performed by a single wafer processing method, it is impossible to overcome an oxidation problem of the interlayer dielectric film.
An object of the present invention is to provide an apparatus for forming a coating film and an apparatus for curing the coating film capable of controlling substrates one by one when the substrates having a coating film thereon are cured while preventing oxidation of the coating film efficiently.
According to the present invention, there is provided an apparatus for forming a coating film comprising;
a coating unit for forming a coating film by applying a coating solution onto a substrate; and
a curing unit for curing the coating film by applying a heating and a cooling to the substrate.
The curing unit comprises
a heating chamber having a hot plate for heating substrates having the coating solution applied thereon, one by one;
a cooling chamber communicated with the heating chamber and having a cooling plate for cooling the substrates processed with heat;
an inert gas supply mechanism for supplying an insert gas to the heating chamber and the cooling chamber; and
an evacuation mechanism for evacuating the heating chamber and the cooling chamber.
It is preferable that the apparatus further comprise, a power source for supplying a power to the hot plate; a first and second temperature sensors for detecting temperature of the hot plate; setting means for setting a first specified temperature which is an upper limit of a temperature range suitable for curing the coating solution and for setting a second specified temperature which is higher than the first specified temperature, a controller and a temperature controller for controlling the power supply such that when temperature detected by the first temperature sensor exceeds the first specified temperature, power supply to the hot plate is terminated, and when the temperature detected is lower than the first specified temperature, power supply to the hot plate is initiated; and an excessive temperature increase detector for terminating power supply to the hot plate when temperature detected by the second temperature sensor exceeds the second specified temperature and maintaining an OFF state of power supply.
In this case, it is desirable that the apparatus further comprise, a relay connected to each of the temperature controller, controller, excessive temperature increase detector and hot plate, for opening and closing a power supply circuit from the power source to the hot plate, that the controller output an opening signal to the relay when power supply to the hot plate is terminated, and that the excessive temperature increase detector output an opening signal to the relay when power supply to the hot plate is terminated.
According to the present invention, there is provided an apparatus for curing a coating film comprising;
a heating chamber having a hot plate for heating substrates coated with a coating solution, one by one;
a cooling chamber communicating with the heating chamber, for cooling the substrate processed with heat;
an inert gas supply mechanism for supplying an inert gas to the heating chamber and the cooling chamber; and
an evacuation mechanism for evacuating the heating chamber and the cooling chamber;
According to the present invention, since an inert gas is supplied to each of the heating chamber and cooling chamber, the heating and cooling can be performed continuously under an atmosphere low in oxygen concentration and the coating film can be sufficiently prevented from being oxidized.
Furthermore, the temperature of the hot plate is detected by using two different temperature sensors and the temperature of the hot plate is controlled on the basis of these detection temperatures. Even if the temperature of the hot plate increases to a high temperature region which a conventionally-employed apparatus cannot control, a thermocouple can control it. In addition, power supply to the hot plate is mechanically terminated by the excessive temperature increase detector. Therefore, it is possible to prevent an excessive increase in temperature of the hot plate. Note that a thermocouple and a platinum resistance temperature sensor may be preferably used as the temperature sensor.
A shutter is provided for blocking the heating chamber and the cooling chamber in the curing unit. Therefore, it is possible to prevent thermal interference between these chambers.
Furthermore, it is preferable that the heating chamber have a ring shutter surrounding an outer periphery of the substrate placed on the hot plate during heating and a lifting mechanism for moving the ring shutter upward and downward. With this constitution, uniformity in temperature of the substrate over the entire surface can be further improved.
In the apparatus for forming a coating film according to the present invention, the curing unit for curing a coating film has a heating chamber for heating a substrate and a cooling chamber for cooling a substrate processed with heat, are provided so as to communicate with each other. In addition, an inert gas is supplied to each of the heating chamber and the cooling chamber. Therefore, the heating and the cooling can be continuously performed under an atmosphere low in oxygen concentration and the coating film is fully prevented from being oxidized.
According to the present invention, wafers are processed one by one in a heating chamber. It is therefore possible to accurately control the wafers one by one. In addition, heat can be kept applying uniformly to the entire surface of the wafer in the hating process. Furthermore, due to the single wafer processing, the wafers can be controlled one by one unlike a conventional case in which the wafers are controlled in lots. It is therefore possible to improve the threshold of the wafer in the heating process.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.